Method of forming a spark plug



E. Bv NOWOSIELSKI METHOD OF FORMING A SPARK PLUG y March 14, 1939.

2 Sheets-Sheet l Filed June 2, 193'? INVENTOR. fdr/vara /Von/os//S'r/ M NEY March 14, 1939, l E, B NOWO5|ELSK| 2,150,725

METHOD OF FORMING A SPARK PLUG Filed June 2. 1957 2 Sheets-Sheet 2 IN V EN TOR.

8 v Edward Nowos//s/f/ STATE@ www@ METHOD F FORWNG A SPARK PLUG Edward B. Nowosieiski, Bloomeld, N. ii., assignor to Eclipse Aviation ilorporation, a corporation ci New .Hersey Application .lune 2, 1937, Serial No. M6892 2 Claims.-

This invention relates to spark plugs, and particularly to those intended for use under severe conditions as to heat development and current intensity, necessitating maximum' efliciency in heat dissipation and in electrode construction. This application is composed of subject matter divided out of my applications Serial No. 16,882

filed April 17, 1935 now Patent No. 2,088,384; Serial No. 29,530 filed July 2, 1935 now Patent No. 2,081,500; Vand Serial No. 62,524 filed February 5, 1936.

Some of the objects are to provide improved electrodes including novel .methods of constructing and assembling the electrodes, and of adjusting the spark gap; to provide improved heat deecting means; and to provide other improvements and advantageous combinations the nature of which will appear.

These and other objects of the invention will become apparent from inspection of the following specication when read with reference to the accompanying drawings wherein is illustrated the preferred embodiment of the invention. It is to be expressly understood, however, the drawings are for the purpose of illustration only, and are not designed as a denition of the limits of the invention, reference being had to the appended claims for this purpose.

In the accompanying drawings forming part hereof:

Fig. l is a View in elevation of one embodiment of the invention; l

. Fig. 2 is a longitudinal sectional View of the plug sh'own in Fig. 1 but on an enlarged scale;

Fig. 3 is a bottom plan view of the plug;

Fig.V 4 is a sectional view of the central electrode in course of formation;

Fig. 5 is a diagrammatic view showing an alternative shape for the electrodes it@ and E09' of Fig. 3;

Fig. 6 is a longitudinal sectional view of a different embodiment of the invention;

Fig. 7 is a bottom plan view of the plug shown in Fig. 6;

Fig. 8 is a longitudinal sectional view of the lower portion of a plug similar to that of Fig. 2 except for the type of grounded electrode construction; and

Figs. 9 to 13 inclusive, indicate the appearance of the element 86 of Fig. 8 as it passes through the successive stages in the process of forming it into its nal condition.

For the purpose of a shielded aviation sparkplug the metal body l0 of the plug is provided with a shield extension il which extends up- (Ci. 29-15 5.5ll)

ward considerably above the upper end of the spindle i2 to enclose the spindle and the electrical connection 02 between the spindle i2 and the conductor 66 which supplies the high-tension current. This extension ii is preferably in one g piece with the attaching nut 5, though such unity is not necessary.

Instead of completely closing the space between the shield extension il and spindle i2, I provides. cooling and Ventilating chamber i3 in E@ the form of an annular space between the shield extension il and a long thin cylindrical metallic sleeve it lined with a tube i5 formed of rolled mica constituting the ywall .of a second chamber which is bounded at its lower end by the upper iid surface of the compressible metal gland l'i, and at its upper end by a novel heat delecting and sealing assembly more fully described, as well as claimed, yin my application No. 16,882 above identied. For a similar reason certain other elego ments are not discussed in detail herein; the detailed description herein being conned to those features which aremore particularly the subject of this application. Among these is the central I spark gap by producing relative angular motion between the parts tilt and 609 (or and 4209) 35 about the common axis of said parts. This adjustment can be eected by inserting in the space between the two elements a gage of proper thickness to give the desired spark clearance and then applying said gage to the elements as a lever to 40 cause one of said elements to turn sumciently to produce the desired clearance therebetween. Electrode i109 is integrated with the recessed end 86 of the shell 3@ by fusing or bonding it thereto through the instrumentality of a joining piece lll of a soft metal similar to that of the sleeve 95 which bonds part itt to spindle i2 in the manner hereinafter outlined in connection with the de-` scription of the central electrode assembly as shown in Figs. 2 and 4. Gland ii of Fig. 2 50 has a tapered surface for registry with a correspondingly tapered seat lili in the shell 30, to supplement the heat dissipating action of the soft metal rods l0, and the openings t0 also aid in such heat dissipation. Also in this embodiment I provide an asbestos heat baille I I3, and

a pedestal ||1 of current conducting carborundum or stainless steel having low heat conductivity to further reduce the amount of heat entering contact spring 6| which maintains the electrode pin 62 in contact with the conductor 66. Cable spacer 11 is free to move upwardly beyond rim ||8 of member 83, but only to the point of contact with the annular rim ||9 on the swivel member |69. The said member |69 is lnternally threaded to receive a correspondingly threaded gland 2| of steel or similar material to rmly grip the inwardly turned end |22 of a metallic corrugated tube |23 which, by reason of the pressure exerted thereupon by the application ofthe nut |2|, is pressed firmly upon the beveled annular seat |24 of a bonding member |25, constituting the means for providing a firm electrical bond betweenI the shielding elements |23 and |69, the latter being in firm contact with the complementary shielding element by reason of the pressure exerted thereupon by the act of tightening the coupling nut 1| threaded to the upper end of the shield extension This nut 1| is shown at 10 (Figs. 1 and 2) as milled out horizontally and also vertically to increase the effectiveness of the hold. This milling provides e'xibility which facilitates establishment of a locked connection by the exertion of inward pressure upon the open ends.

The metallic washer 39, described above, corresponds to the thrust washer 38 of my Patent No. 2,081,500; through this metallic washer pressure is applied to the gland I1 to insure a firm bond or seal along the taper of the gland, thus preventing the escape of the confined cylinder gases, the pressure being applied as a result of `threading the shield extension into the shell 36, substantially as described in my said Patent No. 2,081,500. Also as described in said patent, this firm engagement between the parts |1 and 36 provides an effective path for the heat that flows outwardly through the pressure gland |1 and toward the radial openings in the shell 36.

The e1ectrode @up los is initially of uniform bore, so that it may be slipped over the enlarged base of spindle |2 and its covering sleeve 95 (as indicated in Fig, 4) and then secured in position thereon by a pressure suiiicient to change the cross-section of the upper end of said cup |06 to cause its contour to conform to that of the spindle base and sleeve 95, all said parts being fused into a unitary assembly by the process.

As shown in Figs. 6 and 7 the outer electrode 8 is made in one piece, electrically or otherwise Welded, to the shell along the two cylindrical surfaces indicated at 5 and 6, between which surfaces there is a peripheral groove adapted to be filled by metallic ring 4 of a softer material such as copper having greater heat conductivity so as to facilitate the dissipation of excess heat which might otherwise develop into grounded electrode 8. It will also be noted that although the normal path across which the high tension current will jump includes that portion of the electrode which is directly below the base of the central electrode 1, there is an auxiliary potential spark gap across to the inwardly extending circular ledge indicated at 3; but the primary purpose of this ledge 3 is to constitute a baille to impede an entry into the interior of the plug of objectionable products of combustion.

To conform to standard practice, shell will be made from suitable free-turning steel, while electrode 8 will be made from bendable metal having good spark resistant qualities, as, for example, a nickel-manganese alloy.

Also as shown in Fig, 6, the insulator 20 is of ceramic material such as porcelain, positioned solidly within the shell by the action of threading parts l0 and together. This action holds the insulator 20 against the shouldered portion 30 of the shell, a seal against escape or entry of fluid being effected at this point by the provision of the gasket 3| engaging the shoulder 30, Above this shoulder 30 the insulator may be peripherally grooved, and is also internally threaded as indicated at 33, the grooves being adapted to cooperate with the radial apertures 34 in the shell to establish a path for the circulation of a cooling current of air, and the threads 33 being adapted to cooperate with corresponding threads on a metallic sleeve 35 of copper or other material having good heat conducting qualities, whereby a substantial amount of heat may be taken from the electrode 1 and spindle |4 and transferred through the insulator, to be disspi-rated along the surfaces of the grooves and through outlets 34. Heat not dissipated in this fashion may be transferred to the second region of air circulation around the heat radiating jacket l5, the heat flow path including parts I9, 28, |8 and |6.

Thus the spindle extension I9 which is riveted to the spindle, serves a double purpose: first, it keeps the spring 36 in place, and secondly, it tends to transfer a large measure of excess heat to the copper ferrule 28, for ultimate radiation by way of jacket I5.

In assembling the plug elements the rst step is to braze or otherwise permanently weld the electrode spindle |4 within the metallic sleeve 35, and the second step is to apply a suitable cement to the threaded surfaces 33, so that upon threading the spindle carrying sleeve into the porcelain core 20 to the desired distance, the spindle will become securely bonded to the core 20 by virtue of the cement confined between the registering surfaces of the sleeve 35 and the bore of the core 20. This cementing step, in conjunction with the gasket 3|, renders the plug air and gas tight.

In forming and installing the type of electrode shown in Figs. 8 to 13, the first step is to secure an H-shaped metallic piece 8'6 of suitable heat and spark resisting qualities while at the same time a suiciently good conductor. Such a piece is indicated in Fig. 9. This piece is then subjected to a bending operation to bring it into substantially the form indicated in Fig. 10. Next the parallel sides 81 and 88 are turned into semicircular arcs which preferably do not quite join (as indicated in Figs. 11 and 12) the cross-connecting portion remainingin the form to which it is initially bent, as shown in Fig. 10. The nal step in formation of the electrode is to shape the upper annular surface formed by the semi-circular parts 81 and 88 so that in transverse section it ywill have the final appearance indicated in Fig. 8. When thus completed the electrode receives a thi-n dished washer 9| of soft metal such as copper and then a second dished washer 92 of harder material and preferably the same material as 'the electrode 86 itself. The installation and completion of the electrode assembly is then obtained in the following manner: The shell 36 is placed on a table or work-bench with its lower counter-bore 96 uppermost, a thinl cup-shaped liner 91 of soft metal, preferably the same material as that of the piece 9|, and centrally aper.- 75

tured to a diameter corresponding to the diameter of the chamber 34, cessed end 96. The electrode assembly consisting of the parts 86, 9| position within the inverted cup member 91 and the assembly consisting o the parts 36, 91, 92, 9| and 86, is then placed in a hydrogen gas furnace or other suitable heat chamber and subjected to a temperature sufficient to cause a fusion or welding along the'surfaces of the elements 91 and 9|, with the result that the five elements above enumerated become fused into a permanently welded single unit. This unit is then removed from the furnace, the core assembly, the shield extension assembly, and upper cable assemblies successively attached thereto in the respective manners above indicated. When this complete assembly has been accomplished it will be found that the inner electrode 25 occupies a position approaching that of the transverse portion 8'6 of the outer electrode and also approaching that -of the inner cylindrical edge 99 of the thimble 92, forming an auxiliary spark gap, the clearances therebetween being such that the spark will normally jump from the relatively broad surface of the electrode 25 to the correspondingly broad plane surfaceof the cross-piece 86 of the ground electrode; but if for any reason this normal path of the spark is obstructedas for example by the formation of i then jump from the 25 to the ice particlesthe spark can cylindrical surface of the electrode is then inserted in the rev and 92 is then placed in above described cylindrical surface 99 of the thimble 92 which may therefore be considered as a part of the completed electrode. In fact, it is, of course, possible to have the elements 92, 9| and 86 originally formed as an integral whole rather than being composed of three subsequently united pieces as shown.

What is claimed is:

1. The method of forming a spark plug electrode which comprises the steps of bending the cross-piece of an H-shaped element at points equally spaced from its center, and adjacent the parallel sides thereof, .then curving the sides backwardly toward the center of said H-shaped piece into complementary semi-circular shapes so that the two form an annulus adapted to fit the plug base with the cross-piece joined thereto at diametrically opposite locations.

2. The method of forming a spark plug electrode which comprises the steps of bending the cross-piece of an H-shaped element at points equally spaced from its center, and adjacent the parallel sides thereof, then curving the sides backwardly toward the center of said H-shaped piece into complementary semi-circular shapes so that the two form an annulus adapted to fit the plug base with the cross-piece joined thereto at diametrically opposite locations and then applying sufficient heat to the said plug base and annulus to fuse the two into a single unit.

EDWARD B. NOWOSIELSKI. 

